Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

So let's say I want to run a BT army with either DA, SW or even vanilla marine allies. Would it be wrong to paint the entire army up as black templars? I mean would having a Thunderfire Cannon and a land raider redeemer with BT iconography all over it be wrong?

I could see the thunderwolf cavalry being very strange, but most other things could fit. What do you guys think about using allies but painting and modeling the whole army to look like one unit?

It's fine, with one caveat: You (and more importantly, your opponent) have to be able to differentiate between what is allied and what isn't.

A shoulderpad in a different colour for all the allies is the easiest way. Even just outlining their shoulder pad in a starkly different colour does the trick.

Rings around the bases might work. Even if it's just elastic bands, make them stand out in some way, you can have the model itself the same as the rest.
Vehicles often don't have bases, though.

I've thought about doing similar things with my Crimson Fists. I thought about putting in a bunch of Death Company with Tycho as Rynn's World Ork Hunters, but I'd paint them up like Crimson Fists like everybody else. As long as it's clear what's what and you don't have much in the way of redundant units (for instance, Space Marine Assault Squads and Black Templar Assault Squads) you should be gravy.

Yup, as above.

Easily distinguished (emphasis on easy, don't make your opponent crane his neck to look for tiny differences) and WYSIWYG throughout.

The base colour idea is actually pretty cool.

Well, I was looking to adding regular Tau as allies for my farsight enclave (mainly an excuse for an iridium commander).

If I went through with it, I would just paint them all as the farsight enclave. Since they are battle brothers it really doesn't matter what is an allied detachment and what is the main force.

In your case though, something simple such as the shoulder pad paint option would be necessary to distinguish between marines with BT rules and marines without them. Some armies are lucky and their wargear alone is what separates them, but if your BT marines are equipped the same as the vanilla then it can be hard to tell who is who.

I actually much prefer this approach as it really allows vanilla marine players to beef up their army while maintaining their personal fluff. As long as everything is clear gameplay wise then go for it.